Duet WiFi and stepper motor Failrues



  • Hi All

    Bit of a long one, I keep killing steppers and am now at a loss on whats causing it:

    New build CR10 clone using a Tronsxy as a base, 400x400
    Duet wifi 2.02(RTOS) (2018-12-24b1)
    12V 30 amp power supply, fused at 20amps, with a seperate 30amp supply for bed run through mosfet
    Steppers set to run at 1000ma
    17HS4401S stepper motors on the latest build(see below)
    Steppers are slightly warm to the touch when running on bigger prints, slightly as in 5-10 degrees, not very much at all.
    Dual Z motors wired in parrallel

    I did have a motor with an internal short on the Y axis originally, there was a solder bridge causing me issues with the original build. Repalced with a spare and worked fine after a lot of troubleshooting. I also had 2 of the original cables with internal breaks in the wire (troubleshooting all that was fun!). All fixed, new wires purchased and all repalced.

    Setup the printer with the motors originially supplied, they are nominally 1.5 amp motors but if the quality of the rest of the original is to go by could be anything. After very light usage, just setup and calibration I could stall the X and Y motors with one finger, replace the motor and it went back to usual levels of torque so assumed dodgy motors.

    Have now repalced all steppers with the above 17HS4401S. After calibration and started a long print, and have now killed the Y stepper again. Fitted motor can be stalled with finger, fit a spare stepper and I cant stall it.

    Print qualty is excellent when running, until the motors break down.

    Probably unrelated but worth noting: when I use z hop the z motors do not return, they go up and dont drop down creating a missing layer. Watched it do it with the 20mm calibration cube. Its not intermittent its every single z hop. Have seen this being attributed to binding on z. Can set Z0 and run the carrige to the top and down again back to the same z0 with no odd noises. THis is not what Im asking for help with here, need to solve the motor issues first but figued worth noting)

    So....where do I go from here?

    I did not watch the long print, so dont know if the motor got hotter. Can fit heatsink and fan to motors but really should not have to?

    Noticed a recomendation to ground the motors which I have not done yet.

    I cant keep replacing steppers, they are not that cheap. Any suggestions for things I can test?


  • Moderator

    @idmurp Did you check each of the 'failed' motors on a different stepper driver? Was it just on Y that the motors lose torque? I can't think of anything off-hand that can 'kill' a stepper motor; even if one coil shorts, the other should hold it. Please test the resistance of each coil pair on each motor, if you have a multimeter, as this is really the only way you'll know for sure.

    The problem with the Z hop is, most likely, your acceleration on Z is set to high, though if you only have a motor on one side of Z, could well be binding.

    Also, please post your config.g.

    Ian



  • COnfig.g below

    Tested the steppers using muktimeter, broken ones have identical resistance to non broken.

    Have tested another motor on the Y drive cable and they have the correct torque, not tested the "broken" motors on another cable yet. WIll do once I have finished work

    ; Configuration file for Duet WiFi (firmware version 2.03)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.3 on Tue Nov 26 2019 20:50:06 GMT+0000 (Greenwich Mean Time)
    
    ; General preferences
    G90                                     ; send absolute coordinates...
    M83                                     ; ...but relative extruder moves
    M550 P"CR10 400"                        ; set printer name
    
    ; Network
    M552 S1                                 ; enable network
    M586 P0 S1                              ; enable HTTP
    M586 P1 S0                              ; disable FTP
    M586 P2 S0                              ; disable Telnet
    
    ; Drives
    M569 P0 S1                              ; physical drive 0 goes forwards
    M569 P1 S0                              ; physical drive 1 goes backwards
    M569 P2 S0                              ; physical drive 2 goes backwards X axis
    M569 P3 S0                              ; physical drive 3 goes forwards
    M584 X0 Y1 Z2 E3                        ; set drive mapping
    M350 X16 Y16 Z16 E16 I1                 ; configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E91.00      ; set steps per mm
    M566 X900.00 Y900.00 Z60.00 E120.00     ; set maximum instantaneous speed changes (mm/min)
    M203 X6000.00 Y6000.00 Z600.00 E1200.00 ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E250.00     ; set accelerations (mm/s^2)
    M906 X800 Y800 Z1000 E1000 I30            ; set motor currents (mA) and motor idle factor in per cent
    M84 S30                                 ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                        ; set axis minima
    M208 X400 Y400 Z400 S0                  ; set axis maxima
    
    ; Endstops
    M574 X1 Y1 S1                           ; set active high endstops
    M574 Z1 S2                              ; set endstops controlled by probe
    
    ; Z-Probe
    M307 H3 A-1 C-1 D-1                     ; disable heater on PWM channel for BLTouch
    M558 P9 H8 F500 T2000 A5 R0.5s          ; set Z probe type to bltouch and the dive height + speeds
    G31 P25 X-47 Y-5 Z1.9           ; set Z probe trigger value, offset and trigger height
    M557 X15:385 Y15:385 S30                ; define mesh grid
    
    ; Heaters
    M307 H0 B0 S1.00                        ; disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4138 R4700             ; set thermistor + ADC parameters for heater 0
    M143 H0 S120                            ; set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4138 R4700             ; set thermistor + ADC parameters for heater 1
    M143 H1 S280                            ; set temperature limit for heater 1 to 280C
    
    ; Fans
    M106 P0 S0 I0 F500 H-1.6                  ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45               ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1 F0                        ; define tool 0
    G10 P0 X0 Y0 Z0                         ; set tool 0 axis offsets
    G10 P0 R0 S0                            ; set initial tool 0 active and standby temperatures to 0C
    
    ; Custom settings are not defined
    
    
    


  • Can can confirm that the weak stepper is now weak on both the X and Y Axis circuits. If I plug a new motor into either of those circuits it works fine.

    The stepper is now at fault, and its the 3rd occuance in 2 different makes of steppers on this printer which has hardly seen any use.


  • administrators

    Do the stepper motors have permanently-wired cables, or detachable cables?


  • Moderator

    @idmurp said in Duet WiFi and stepper motor Failrues:

    17HS4401S

    Are these the motors? https://www.amazon.com/Usongshine-nema-17-Stepper-Motor/dp/B07KW6B3ZX?th=1

    Rated current is listed as 1500ma and you have 800ma set. It's generally recommended to use 70-85%. So 800 is a little low which could explain the lack of torque. Try 1200ma.

    I've never seen anything like multiple motor failures like this before. I would expect a driver to go before a motor.



  • @dc42 Permenant wires

    @Phaedrux yes they are the motors, they have good holding torque at 800 to start with but that declines?

    Im really confused as well, I cant find anything like it online either. But 3 failed motors...


  • administrators

    @idmurp said in Duet WiFi and stepper motor Failrues:

    @dc42 Permenant wires

    One of the most common causes of weak motors is a bad crimp connection between the cable and the crimp pin in the Duet connector. Have you tried crimping a new connector on the leads of one of the failed motors?



  • @dc42 No but I have swapped the motor for a new one, which worked fine. Then put the old one back on and that still had the low torque



  • okay as it does not seem to be anything obvious. I know this has happened twice on Y so.

    Printer is not earthed so earth it
    I believe I can remap extruder 2 stepper to be the Y drive so do this.
    Use a new fresh and tested cable
    Use a new motor for Y drive.
    Put a cooling fan on Y drive stepper
    bump all of them up to 1200 ma

    This gives me a essentially fresh start on the Y drive.

    is there any chance it could be power supply related? I could swap the power supplies over and use the current heated bed supply for the board.

    Then hope....

    Any other suggestions?


  • Moderator

    The only thing that seems unique to your setup is the dual power supply. can you post how you have it all wired up?

    Lack of grounding is concerning. How is it grounded now?



  • @Phaedrux said in Duet WiFi and stepper motor Failrues:

    The only thing that seems unique to your setup is the dual power supply. can you post how you have it all wired up?

    Lack of grounding is concerning. How is it grounded now?

    240V to the 2 power supplies from a common plug.

    First power supply, 30 amp on a 20 amp fuse powers the board

    The second power supply just provides power to the mosfet that powers the bed, 30 amp fuse, it is not connected in any other way to the printer. I can run the printer with the second power supply disconnected alltogether if I dont want a heated bed.

    Its a 400X400 printer, I need close to 30 amps just for the bed and had 2 30 amp power supplies to hand.

    They do share a common earth bar, something I might change though I dont see how that would affect anything.

    The power supplies are grounded, there is no ground on the board or printer itself. WIll ground the printer next


  • administrators

    @idmurp said in Duet WiFi and stepper motor Failrues:

    @dc42 No but I have swapped the motor for a new one, which worked fine. Then put the old one back on and that still had the low torque

    If the cables are not detachable from the stepper motor, you must have used the new cable that came attached to it. That's why I suspect the crimp connections.



  • @dc42 Cables came with it but not attatched, they are plugged into the stepper via a removable plug.

    In other news this looks similar to my problem and was blamed on static build up...

    https://forum.tiertime.com/t/extruder-driver-failing/545/4?fbclid=IwAR3OuNbYLukdrEG0CF6_pnnZ4PIy_lhVgHU2gJlcPu0u0v7wOYpwuTv9UTc



  • In way of an update I have:

    Replaced Y drive and succesfully tested other steppers
    Repalced Y drive cable
    Remapped Y drive to extruder 2
    Grounded the printer

    I am rerunning the setup and calibration today
    Tomorrow Ill work from the same room as the printer and set a long print running, will give me 8-9 hours to monitor temps etc to see what happens


  • administrators

    @idmurp said in Duet WiFi and stepper motor Failrues:

    @dc42 Cables came with it but not attatched, they are plugged into the stepper via a removable plug.

    In other news this looks similar to my problem and was blamed on static build up...

    https://forum.tiertime.com/t/extruder-driver-failing/545/4?fbclid=IwAR3OuNbYLukdrEG0CF6_pnnZ4PIy_lhVgHU2gJlcPu0u0v7wOYpwuTv9UTc

    Our wiki page https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Connecting_stepper_motors includes this:

    Note: it is highly recommended that the stepper motor casings be grounded, especially in belt-driven printers. Otherwise, motion of the belts causes static charge to build up, which eventually arcs over to the windings. If the motors are screwed to a metal frame, grounding the frame is sufficient.



  • So I have done all of the above and have now done a reasonable amount of test prints without killing a further stepper....so far. Im suspecting it was static build up, but cant be sure

    Have other problems now but all fixable.

    Will update further if I do kill another stepper, but so far so good!


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